1. Field of the Invention
The present invention relates to a speaker device configured to generate a transverse wave.
2. Description of the Background Art
There has long been known a speaker device each having a plurality of horn-shaped, cone-shaped speakers responsive to different audio frequency ranges (low-frequency range, mid-frequency range, high-frequency range) attached to a baffle plate on the front surface of a speaker box thereof.
A plane-shaped speaker device without a speaker box has also been disclosed in patent document 1 (Japanese patent publication No. H4-64240) and patent document 2 (Japanese patent publication No. H3-79920).
The plane-shaped speaker device has been configured such that a sheet-like diaphragm having the front surface thereof fixedly attached with a plurality of ribs is maintained at a bending state of the diaphragm thereof, and such that the diaphragm is causes to vibrate through a plurality of voice coils having different audio frequency ranges provided in a dotted pattern on the back surface of the diaphragm curved by bending.
Due to the fact that the plurality of ribs hinder vibration of the sheet-like diaphragm, it has been well known that the speaker made of the sheet-like diaphragm is lower in performance in reproducing a high-frequency range and a low-frequency range than in reproducing a mid-frequency range.
It has been proposed in patent document 3 (Japanese patent No. 2510607) that a plane-shaped speaker device having an opening formed in the center of a sheet-like diaphragm as well as having added thereto a cone-shaped speaker dedicated to a high-frequency range in the opening configured to reinforce performance in reproducing a high-frequency range.
A conventional speaker device had the following problems:
[1] A speaker device attached with a plurality of horn-shaped, cone-shaped speakers is suitable for reproduction of a plurality of audio frequency ranges, and is characteristic of high directivity of sound; however, the speaker device generates a compression wave (longitudinal wave) in the air. As a result, there has occurred a problem that a compression wave (longitudinal wave) in the air worsens propagation properties of sound and therefore sound is attenuated in proportion to a distance, and that interference of a compression wave occurs.
In addition, a compression wave (longitudinal wave) in the air emitted as sound from the speaker device has rendered conversation as being difficult in a loud-sound environment.
[2] A plane-shaped speaker device can be compact in size; however, it is low in performance in reproducing a high-frequency range and a low-frequency range.
For example, sound having a high-frequency range such as that in music played with a stringed instrument and that in an opera may become opaque easily and cannot be reproduced clearly. In addition, sound having a low-frequency range such as drum sound and base sound is hard to reproduce.
[3] For a plane-shaped speaker device obtained by combining a sheet-like diaphragm and a publicly-known cone-shaped speaker, it has been technically difficult to adjust a balance of a sound volume between the cone-shaped speaker and the sheet-like diaphragm.
[4] For a plane-shaped speaker device, there still remains a problem that a maximum sound volume thereof is lower than that achieved by a cone-shaped speaker.
Increase in the sound volume of the plane-shaped speaker device beyond limits thereof has caused sound clipping (the so-called, chattering noise) to occur.
[5] For the reasons provided above, many problems have still been left as being unsolved with respect to a plane-shaped speaker device, which has delayed practical use thereof.
The present invention has been made to solve the above problems, and the object thereof is to provide at least one of the following speaker devices:
[1] the speaker device capable of emitting sound having a mid and high-frequency range as well as sound having a low-frequency range, at high quality, while a component count is suppressed;
[2] the speaker device for which effective use can be made of a drive unit thereof;
[3] the speaker device having a sound volume increased by enhancing bending deformation performance of a diaphragm thereof;
[4] the speaker device having a high degree of healing and peace-of-mind effects; and
[5] the speaker device added with a high value having the function as an interior ornament as well.